Over the years there has developed a significant market for progressively smaller cameras, frequently designated as "miniatures". These cameras find a ready market for those users who want an extremely compact light-weight camera. Well known among these cameras are those designed to work in conjunction with an industry-standard miniature film cassette generally known simply by the designation "110". This cassette features two generally lobe-shaped sections, one for dispensing the film, the other for winding it about a self-contained take-up spool, the two lobe-shaped sections extending generally towards the scene to be photographed, the sections being joined by a rectangular channel-shaped conduit through which the film is advanced, the conduit being open along the forwardly facing region thereof, Cameras designed to accept these cartridges are normally configured with a loading aperture of one sort or another at the back of the camera and a pair of chambers on either side of the imaging station for insertingly accepting the cartridge dispensing chamber and take-up chamber respectively, so as to place the film conduit centrally disposed on the optic axis of the objective lens of the camera. In an effort to reduce cost to an absolute minimum, certain cameras have occasionally in the past been designed without a conventional loading door and so as to permit direct insertion of a 110 cassette through the permanently open back of the camera, the walls and interior contours of the camera being configured to produce a light-tight seal.
With respect to such cameras which do not have a loading door, but which use the film cartridge itself to seal the back of the camera, unlike the most advantageous form of the present invention to be described, there was no simple and inexpensive protection of the camera interior against dust or other foreign objects when the cartridge is removed in the absence of a separate casing to contain it.
Also, although the 110 camera is in itself a small camera, the doorless cameras described above were not made in the miniaturized form of the present invention. Thus, U.S. Pat. No. 3,138,084 granted June 23, 1964 to D. C. Harvey has a camera housing which is open at the back to receive a 126 film cassette. However, the cassette is located within the confines of the top wall of the camera so that the overall dimensions of the camera are not reduced by the fact that the cassette fits into a doorless opening at the rear of the camera.
Further, it is always desirable to produce as inexpensively as possible a measure of protection against accidental tripping of a cocked shutter, so as to avoid wasting a frame of film.
A further problem from a cost-economics standpoint has to do with cocking the shutter of an unloaded camera. The take-up spool of the 110 cassette has affixed thereto a drive gear which partially extends via a light-tight passage in a forward direction out of a lower portion of the cassette. The corresponding chamber of the camera is provided with a drive gearing system which engages the take-up spool gear when the cassette is inserted, so that actuation of the drive gearing by conventional means causes the take-up spool to rotate to advance the film. Shutter cocking is normally achieved by means of a spring-loaded member coupled to the shutter system which engages an edge perforation of the advancing film, to be cocked by the motion thereof. Since this same motion is indicative of the film travel, the same advancing stroke of the film-engaging member is used to mechanically limit film advance so as to index each frame.
Such simple systems are quite cost-effective; however, if there is no cartridge in the camera, such a cocking motion of the film-engaging member cannot be induced. Thus, if one wishes to test the camera shutter when its operation is suspect, one procedure is to carefully manually engage the cocking member and move it to a cocking position so that the shutter may thereafter be actuated. A significantly costlier approach is to add some other form of coupling mechanism to the camera so that upon actuation of the film-advancing mechanism coupled to the take-up spool, i.e., most typically a thumb wheel, the coupling mechanism will take over the shutter cocking operation when no cassette is present. If cost is to be held to an absolute minimum, it is desirable to avoid the need for such coupling mechanisms.